If you look in the ebuild referred to in the Gentoo Wiki article (see the link in that article), you'll see some chmod commands. I don't have a Lexmark printer and so do not know whether or not those directories exist in your case, but you could try those commands from the command line, or at least study them to give you an idea what to look for. Other than that, I'm sorry but you're own your own as I have no idea about Lexmark printers. Also, looking at the Gentoo Wiki article, my guess is that you would need to use an old version of CUPS (1.3.x) that uses the usblp module. To be honest, I think you're flogging a dead horse. Sorry.

@Fitzcarraldothank you for your answer.You have me persuaded, it's not a true problem because I print with VirtualBox, but I say by myself: computer dont tell me: your printer is too old, but printer and pc dont communicates. One year ago, with Debian32, Arch32, Sabayon32 (Slack no, my printer never worked with Slack) printer was working, the problem is born because I change my architecture 32>64bit.Ok, Ok, no problem, I will spend my money, perhaps 80-100€ (!!!) , for a new printer.CiaoGrazie againjames